Zeng Xiaowei, Zeng Zhanghui, Liu Cuicui, Yuan Weiyi, Hou Ning, Bian Hongwu, Zhu Muyuan, Han Ning
Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Institute of Genetics and Regenerative Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China.
Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Institute of Genetics and Regenerative Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China.
Plant Physiol Biochem. 2017 Jun;115:97-106. doi: 10.1016/j.plaphy.2017.03.013. Epub 2017 Mar 19.
Autophagy is a highly conserved degradation pathway among eukaryote cells, which can recycle damaged or unwanted cell materials upon encountering stress conditions. As a key component of the Class III PI3K kinase complex, ATG6/Beclin-1 is essential for autophagosome formation. In this study, we isolated a putative HvATG6 gene in barley genome. The protein encoded by HvATG6 shares high sequence identity to ATG6 orthologs in rice and wheat, and has a typical autophagy-specific domain containing segments of repeated β-sheet-α-helix. The expression of HvATG6 protein restored the appearance of autophagosomes in yeast atg6 mutant, indicating that HvATG6 complements the deficiency of yeast ATG6 protein in autophagy. Punctate florescence signals, considered as the PAS for autophagosome initiation, were observed in the cytoplasm of cells when HvATG6-GFP fusion construct was transformed into barley protoplast. Furthermore, the expression of HvATG6 was upregulated by various abiotic stresses including dark, HO treatment, nitrogen deficiency, high salinity, drought, low temperature and toxic aluminum. Knockdown of HvATG6 in barley leaves through barley strip mosaic virus (BSMV)-induced gene silencing led to accelerated yellowing under dark and HO treatments. Based on the above findings, we propose that barley ATG6 plays the similar role as other plant ATG6 orthologs, and might be involved in stress-induced autophagy process.
自噬是真核细胞中一种高度保守的降解途径，在遇到应激条件时，它可以循环利用受损或不需要的细胞物质。作为III类PI3K激酶复合物的关键组成部分，ATG6/Beclin-1对于自噬体的形成至关重要。在本研究中，我们在大麦基因组中分离出一个假定的HvATG6基因。HvATG6编码的蛋白质与水稻和小麦中的ATG6直系同源物具有高度的序列同一性，并且具有一个典型的自噬特异性结构域，其中包含重复的β-折叠-α-螺旋片段。HvATG6蛋白的表达恢复了酵母atg6突变体中自噬体的出现，表明HvATG6弥补了酵母ATG6蛋白在自噬中的缺陷。当将HvATG6-GFP融合构建体转化到大麦原生质体中时，在细胞的细胞质中观察到点状荧光信号，该信号被认为是自噬体起始的吞噬泡前体结构（PAS）。此外，HvATG6的表达受到包括黑暗、过氧化氢处理、氮缺乏、高盐度、干旱、低温和有毒铝在内的各种非生物胁迫的上调。通过大麦条纹花叶病毒（BSMV）诱导的基因沉默在大麦叶片中敲低HvATG6导致在黑暗和过氧化氢处理下加速变黄。基于上述发现，我们提出大麦ATG6与其他植物ATG6直系同源物发挥相似的作用，并且可能参与应激诱导的自噬过程。
